Printing roll



Aug. 11, 1942. H. 1.. BOARDMAN ETAL 2 5 PRINTING ROLL, v v

Filed March 17, 1941 Gl EIQELI HARD RUBBER Fig. 11

ATTORNEY Patented Aug. 11, 1942 PRINTING ROLL Harry L. Boardman and Merwyn L. Hendrix, Longview, Wash.

Application March 17, 1941, Serial No. 383,756

7 Claims.

This invention relates to rollers carrying hard rubber printing pads for watermark rolls in paper making machines or for any purpose such as printing where such rolls may be found useful. An important purpose is for watermarking as indicated.

Watermark rolls bearing engraved indicia are known and used to some extent, the engraving being done on a previously prepared hard rubber surface; and also various types of Watermark rolls are known, bearing interchangeable printing dies of metal or other substance affixed to the roll perimeter in several ways. The disadvantage in the current art is the high cost of making a suitable roll and many large jobbers and retailers of paper are thereby excluded from handling paper with their own watermark.

It is the principal object of the present invention to teach the construction of a roll of the character described, that possesses all of the good qualities of rolls made by other processes yet costs only a small part of the cost necessary before our invention.

It is another object of the present invention to devise a method of making a watermark roll in such manner that the web of paper passing under it, in course of manufacture, may readily be watermarked in longitudinal strips so that the maker can assemble a series of short rolls, each bearing the watermark insignia of a different customer whose order he may have, make a Wide web of paper, and divide the finished paper web longitudinally, which makes it easily possible to watermark comparatively small orders economically.

It is a further object to provide an economically built printing roll for inking, useful for rinting sacking to be made up into bags and for many other uses that will at once occur to those familiar with the art.

In the following specification we will illustrate and describe the watermark roll and its manufacture and use, but not with the intention of limiting the scope of the invention, which is to be ascertained from the language of the claims.

A drawing accompanies and forms a part hereof, serving to illustrate a practice of the invention as applied to a watermark roll. Though this as stated, is only one of its useful employments, it contains with the following specification, sufficient teaching so that those skilled in the art may make up any form of it that is desired.

In the drawing:

Fig. I shows a part of a plural element watermark roll in plan with hard rubber printing plates bonded to its perimeter;

Fig. II is an end View of Fig. I; and

Figs. III and IV respectively are plan and elevation of the printing pads adapted to be affixed by bonding to a roll of the character shown in Fig. I.

Watermarking, and indeed almost any kind of printing, requires an unyielding type surface if the outlines of design or letters of a legend thereon are to be sharp and distinct, but on the other hand, a printing pad of hard rubber cannot be made to conform to an arcuate surface unless the mould is also arcuate with the proper radius; which means a set of moulds for each diameter of roll and the invention herein resides in the discovery of how to overcome this difiiculty. We will now describe the method of doing it.

We first make one or more moulds in relief, which may be done by movable type according to the known art; then We use these to make up a sufficient number of negative moulds in intaglio of plastic, also well known. These are already used in the well known rubber stamp of which examples are common in every office. We take one or more moulds, just as would be used in making rubber stamp facings, and load them with sufficient material, either a rubber composition or synthetic material so compounded or possessing the characteristic of vulcanizing hard upon the application of heat and pressure for a sufficient length of time. The art needs no further instruction about how to do this. The compound must be capable of vulcanizing to an interim stable, yet flexible condition, and with a natural rubber base this stage can be attained with say 300 degrees F. heat and from five to fifteen minutes of time, after which the partly vulcanized pads with their moulds are removed from the press and allowed to cool. If it appears necessary to get exactly the right thickness, the moulds containing the partly vulcanized pads may now be affixed to the table of a grinding machine and passed under a wheel surfacing the back of the pads 2 to precisely the required thickness, after which the pads are stripped from the moulds.

We next prepare the cylindrical roll 3, which will of course have been properly machined, by coating it evenly with a coating of the well known bonding cement; then afiixing the partly vulcanized pads to the surface by pressing them in place when the cement is tacky, to which they will firmly adhere under these conditions. These pads should be pressed from the center towards the edges and a wood mallet can be used to advantage, it being necessary to drive out all of the air from beneath them. For ordinary uses the roll is now ready for finish vulcanizing, which may be done by placing the roll in a retort or oven and maintaining 300 degrees F. of heat from four to twenty hours, depending upon the degree of hardness required. For a watermark roll they should be bone hard or nearly so because these rolls are heavy and the tendency of rubber to displace laterally under pressure being what it is, there is a strong tendency to displace the fibers of the partly made paper and damage it if the design yields any.

For especially sharp lines on the legend or design, we may cover the design pads or even the whole roll with plaster of Paris, which is allowed to set, then the whole roll is wound with fabric after the known manner, whereupon when the roll is subjected to vulcanizing temperature, the expansion of the roll itself by heat will result in high pressure on the pads. This is not considered necessary for a Watermark roll but may be desirable in some types of printing work, especially in printing cloth for sacking.

Where, as hereinbefore stated, it is desirable that a number of short rolls be assembled on a single shaft to mark paper web in zones with different Watermarks, we prefer to provide each section of the whole roll with spiders such as 5 and intercepting joints as diagrammatically indicated at 6, whereupon end pressure as by a threaded portion of the shaft on one end, a shoulder on the other and a nut, may keep all of the roll surfaces in surface registry.

It will be seen at once that we have solved the problem of constructing a printing roll with a hard rubber printing surface that is truly cylindrical with respect to all parts of the legend or design that constitute the printing surface, because we may use force in sufiicient amount to make the relatively flexible partly vulcanized pads conform to the roll and no permanent distortion of the letters or design will result; then we vulcanize hard with the aid of bonding cement when, as is well known, the bond is permanent up to damaging force being so applied the printing surf-ace is destroyed. It will also be found that this automatically solves the problem introduced by crowned watermark rolls.

In this specification and in the claims, the word rubber is used in its broadest sense, to include materials natural or compounded that possess the property of vulcanizing to hardness by application of pressure and heat and also possess the capability of being bonded to a metal surface by a vulcanizable bonding cement, whether or not such material contains any natural rubber.

Having clearly disclosed our inventionin the manner provided by the patent statutes, what We claim as new and desire to secure by Letters Patent, is:

1. As a new article of manufacture, a printing roll comprising a metal roll member adapted for revolution, and a plurality of hard vulcanized pads bearing insignia vulcanized in place thereon, the surfaces of the insignia being arcuate, the several arcs thereof being concentric with the surface of the roll.

2. As a new article of manufacture, a metal roll adapted for revolution in printing and a printing surface thereon in which moulded hard rubber insignia in relief are vulcanized to the surface of the roll with all printing surfaces of said insignia arcuate and concentric with the arcuate surface of the roll.

3. 'As a new article of manufacture, a printing roll comprising a roll portion with moulded hard rubber printing insignia vulcanized in place on the perimeter thereof, the printing surfaces of such insignia being in concentric relationship with the surface of the roll.

4. The method of making a printing roll bearing hard rubber printing surfaces which consists of making a mould of the desired printing in intaglio, pressing and partly vulcanizing suitable rnbber-like material into the mould and partly vulcanizing until it is stable but still flexible, then removing the rubber from the mould and cementing its reverse face to the perimeter of the roll with bonding cement, then vulcanizing hard in a heated chamber while protecting the design of the printing surface from distortion.

5. The method of producing a printing roll having a printing surface of hard vulcanized material bearing relief type characters or the like on a metal base, which consists of preparing the printing surface of vulcanizable material bearing the characters, in a fiat mould, partly vulcanizing the same until it is stable with respect to the characters in relief yet flexible enough to bend accurately to the arcuate surface of a roll,

applying bonding cement to the surface of the metal roll, flexing the partly vulcanized material and sticking it to the surface bearing the bonding cement and then finishing the vulcanization to hardness by subjecting the roll and its carried partly vulcanized material to vulcanizing heat until hard.

6. The method of producing a printing roll bearing hard rubber indicia for printing purposes, which consists of preparing sheets of rubber by moulding the indicia on one surface thereof, and partly vulcanizing the same to a stable yet flexible condition, coating a metal roll surface with bonding cement, sticking the flexible sheets to the cement with the insignia outwards, covering the insignia with soft plaster of Paris, permitting the plaster to set and vulcanizing hard by heating the roll and applied substances in a heated chamber, then removing the plaster.

'7. The method of making a printing r011 with applied hard rubber printing devices which consists of preparing a roll surface by applying vulcanizable bonding cement, applying rubber printing plate structure bearing insignia that has been partly vulcanized to stable yet flexible condition, applying a mix of plaster of Paris over the rubber structure, allowing the plaster to set and then vulcanizing to hardness by means of a heated chamber within which the roll bearing the rubber and plaster is placed.

HARRY L. BOARDMAN. MERWYN L. HENDRIX. 

